Conventional means for locating persons, animals or moving objects often utilize a radio transmitter adapted to be worn by the person or mounted in the movable object, such as a vehicle, which is activated by receipt of an emergency signal containing a unique address code for the radio transmitter. Once activated by a signal or automatically after the passage of a period of time, the radio transmitter sends out a homing signal. The homing signal is then tracked by radio direction finding and distance measuring equipment which indicates the transmitter's direction and distance.
Some locating devices contain "patch-through" systems, whereby a mobile transceiver communicates with complex location finding beacons. The beacons process the transmitted signals to determine and, subsequently, to transmit the precise location of the object to the remote base-station.
Still other devices utilize a transmitting device, attached to a person confined to a specific location, e.g., a person on probation or house arrest. The transmitting device generates signals to a base-station, such as a police station, when the person moves outside the specified location. However, the communication in these devices is usually one-way, i.e., from the transmitting device to the base-station. If the transmitting device does not receive a signal from the base-station, it will not alert the person on whom it is placed when that person moves outside the specified location.
Another locating device operates by continuously determining the position of an object relative to a predetermined acceptable route between two points and generating an exception report upon the object's movement outside of that route. The exception report is then transmitted to a remote central dispatcher. One disadvantage of this approach is that there is no indication to the user of the object of its position outside the acceptable route so that the user may return the object to the acceptable route.
Thus, conventional devices for monitoring and locating people or objects present several disadvantages. They do not provide for: continuous monitoring of the location of one or more children within a specified area, automatic warning to both an observer, such as a parent, and to each of one or more persons being observed, such as children, that one or more of the children has moved beyond the preselected distance from a base-station, automatic generation of homing signal or signals if the child or children do not return within the preselected distance within a preselected delay period, automatic indication to the parent that the child or children have remained beyond the preselected distance for longer than the preselected delay period, continuous locating of the child or children based on the detection of homing signals, and automatic resumption of continuous monitoring of the child or children which return within the preselected distance from the base-station.